Discussion on the localization of APMP pulping pro

2022-08-14
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Talking about the localization of APMP pulping process and key equipment

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apmp (alkaline peroxide mechanical pulp) is translated into Chinese as alkaline hydrogen peroxide mechanical pulp. It is an energy-saving and environment-friendly Pulping Technology launched in the 1980s, with outstanding advantages such as high yield, high whiteness, high strength, low pollution, low water consumption, low energy consumption, low material consumption, etc, Known as the latest pulping technology in the 21st century, it has attracted the attention of the world's pulp and paper industry. Many developed countries in the world have begun to adopt this pulping technology and have followed suit. At present, foreign countries mainly focus on the research of wood fiber pulping, and have achieved success in the application of poplar, eucalyptus, spruce, pine and other pulps for papermaking and cultural paper. The research on non wood fibers is still in its infancy. Andritz, Springfield of the United States and HYMAC of Canada have this technology.

in recent years, domestic colleges and universities, scientific research institutions and other scientific research institutions have carried out extensive and in-depth research on APMP pulping, but the scope of research is mostly limited to the experiment of wood fiber, which is positioned according to the goal of building a strong province in the new material industry, such as China pulp and paper research institute, South China University of technology, Dalian Institute of light industry, etc. The pilot test demonstration line of APMP localization pulping developed by Xi'an Paper Machinery Factory (Xi'an machinery design and Research Institute of light industry) has achieved the localization of all equipment, and the localization rate of its key technologies and key equipment has reached 100%. We have carried out a large number of repeated tests, and have successfully developed APMP cotton stalk and other pulping systems. Through the tests, we have reached the requirements of high-strength corrugated paper gbl910-89 class A, and overcome the difficulties of non wood fiber APMP pulp. On this basis, the project unit has developed APMP technology with two-stage impregnation, two-stage extrusion and two-stage grinding, which is pollution-free, low energy consumption It is suitable for wood and non wood fiber pulping (Asparagus, hemp, bamboo, Sophora japonica branch, Salix psammophila, branch wood, poplar, peptide, etc.) provide a broader pulping space for the company to perform in accordance with relevant laws and regulations. This marks a major breakthrough in APMP pulping technology in this project.

1 Comparison between APMP pulping technology and other pulping processes

APMP is the use of caustic soda, H2O2, EDTA, MgSO4, Na2SiO3 and other chemicals to pre dip wood chips in the It can be ground into pulp under normal pressure, and its whiteness can reach 60%. It is used for making offset paper or magazine paper. To further improve the whiteness and make more advanced cultural paper, it can also be pre soaked twice or three times. Poplar, Pinus massoniana, bagasse, awn stalk, reed, etc. can produce 50% - 75% SBD chemical mechanical pulp under their respective appropriate process conditions for the production of paper, offset book and journal paper, low weight coating base paper and other matching paper. If you want to produce APMP pulp with whiteness above 80% SBD, you can also achieve it by proper peroxide bleaching. Its strength fracture length is more than 3km. For example, the whiteness of paper made with giant tail according to APMP 25% ~ 15%, ground wood pulp 60%, deinked old newspaper 15%, chemical wood pulp 0% - 10% is above 53% ISO, the breaking length is close to 3.2km, and the tearing index is above 5.0mn · m2/g, which meets the requirements of paper gbl910-89 a.

1.1 process characteristics of APMP

wood chips are washed with water to remove heavy impurities such as sediment, and then steamed to 60 ~ 70 ℃. On the one hand, the wood is softened, on the other hand, the air in the wood chips can be removed for future impregnation. The wood chips softened by steaming are longitudinally arranged into filiform or even fluffy shapes during extrusion and then suddenly released, and the dryness can reach 60% - 75%. At this time, the wood wool can fully and evenly absorb the liquid medicine in the impregnation section, react and soften in the subsequent steaming section, and then grind into pulp after 2-3 stages of refining treatment. The fine fiber bundles and sawdust contained in the ground pulp are screened and purified to make qualified pulp. According to the quality requirements, the slurry can also be squeezed and milled in the second stage - prepreg - steaming. The process characteristics of APMP pulping are as follows:

(1) before pulping, wood chips go through a special mechanical treatment process, that is, the extrusion and milling process with high compression ratio (extrusion and dredging machine) is used to make the chips form filaments or even fluffy, so it is very easy to accept chemical treatment and soften, obtain ideal pulping effect, improve the quality and strength of pulping, and reduce the power consumption of pulping by about 1/2.

(2) pulping and bleaching are completed at the same time, and all processes are carried out under normal pressure. However, the process and equipment are relatively simplified, and its economic scale is small, which can generally be 100-150t/d. its infrastructure investment is small, and it is easy to start.

(3) the production water can be recycled, the chemicals do not contain sulfide and chloride, the pollution load is low, the drainage is easy to treat, and is not constrained by environmental factors. 

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